The actress talks with THR about Amelia's past resurfacing as well as whether Meredith and Alex are a romantic relationship just waiting to happen.

[Warning: This story contains spoilers from Thursday's "Roar" episode of ABC's Grey's Anatomy.]

Amelia's (Caterina Scorsone) deepest, darkest moment is out of the bag on ABC's Grey's Anatomy, only the person who needs to know it the most is not the one who knows her secret.

During Thursday's episode, Amelia — fresh off her pregnancy disappointment — struggles with losing a young patient and suddenly her past comes flooding back.

After believing that she was pregnant in last week's episode of the Shonda Rhimes drama, her patient's death triggers memories of the baby she had during her time in L.A. — the baby boy who was born without a brain that was the direct result of Amelia's struggles with narcotics. The so-called "Unicorn baby" featured on Grey's Anatomy spinoff Private Practice has remained a secret from everyone as Amelia never told Derek or Meredith. Now that secret is starting to come between Amelia and her new husband, Owen (Kevin McKidd), who has made no secret during his time at Grey Sloan that he longs to be a father.

During Thursday's hour, Amelia tells Owen that she wants to wait to have children and focus on being newlyweds. But in reality, she's struggling with her past and holding on to the secret of her Unicorn baby from everyone except one unlikely candidate: Alex. Reeling from the loss of a young patient, Amelia winds up telling Alex everything.

Below, Scorsone talks with THR about why Amelia never told anyone, why she's afraid to open up to Owen and what she thinks of Meredith and Alex as a potential romantic pairing.

Amelia hasn't told Owen about her "Unicorn Baby." He's proven to be very accepting of who she is. Why is she worried he'll reject her now?

I think it goes in two directions. One is she knows how fundamental having children is to Owen's identity and his desires for life and she really wants to give him everything that he wants. She loves him so much and she wants to be the person who can make him happy. But she's really terrified that there's something about her and having babies that isn't going to work out and that would be devastating to both of them. I'm not saying it's conscious; she's a doctor, her fears are not necessarily conscious but they're there. And second, in terms of her journey, yes, he's been very accepting but this is a very core trauma for Amelia and there's something about trauma that goes beyond logic. When someone has undergone serious trauma, regardless of whether you think objectively — "Yes, this person is going to be very patient and accepting of it" — but there's something in the nature of trauma itself that makes whatever it was that traumatized the person almost unsayable. I think that's what she's experiencing: even to speak it is to re-traumatize herself in some ways. I think this is a powerful combination of perfect storm factors in her paralysis. She doesn't want to disappoint him, she loves him so much and she is also totally paralyzed by the fear and trauma she went through in Los Angeles.

Alex is inspired to have family breakfasts — with Amelia included. As Amelia is trying to run from her trauma, how might Amelia respond to these get-togethers? It almost sets the stage for something like this to come out.

Maybe! One thing that was a really amazing discovery for Amelia was that she was able to say the unsayable thing to Alex. And she's wanted to say it to Owen this whole time; she wanted to say it to Derek; she wanted to say it to Meredith; and she was not able to tell them. It was too hard. And for some reason, in that moment, in that room with Alex — who has his own demons and is dealing with his own marginalization and his own childhood stuff and emotional disregulation at times — in that moment, she was able to say the thing that she has not been able to say. That was a bit of a revelation for her: there is at least one person in the world that she was able to speak to about that thing. Alex wanting to include her, Amelia seems to find him to be a safe place. And that's nice. Justin and I haven't had much together so far so this is a new acting partner in some ways. We've been in group scenes together but haven't had a lot of one-on-one. It's nice that these two wounded characters are finding a way to talk to each other.

Speaking of Alex, there's a strong contingent of viewers who see Alex and Meredith as MFEO, to use Shondaland speak. The scene at the end of the episode with them together — in bed — really seemed like that could be a real thing. What's your take on them together romantically?

They're two of the original characters so everybody wants whatever is going to make them the most happy. I don't know if it's end game romantically but they will definitely be in each other's lives forever. But again, just like every other fan in Shondaland, I cannot predict what she could possibly be wanting to spin for the very end. We don't know how long the show will go on! There have been so many potential end games that came and went because the show just keeps going. So who knows!

What does Amelia want for Meredith?

I would just want her happy.

Given everything that Meredith and Amelia have been through, will she lean on her sister as she debates opening up to Owen about her baby?

I don't know the answer to that yet because I haven't seen the scripts. So far, Amelia is pretty walled off and is basically isolating — which is typical of her. I'm sure it'll take a toll on everyone around her. She's not acting out; she's just withdrawing. She's so scared and horrified of her own reactions to what's been going on that she just wants to retreat. She's trying to find a quiet place for herself to gather her thoughts and get back in control of this flood of emotions that has hit her. I don't know who she's going to talk to on the way to talking to Owen.

What do you think of Amelia's struggles? Sound off in the comments below. Grey's Anatomy airs Thursdays at 8 p.m. on ABC.